Roberto (Michael Brandon) is a young handsome drummer playing in a rock band. For the last week he has been stalked by a mysterious guy with dark sunglasses. Roberto decides to put an end to this and follows his stalker in a deserted theatre. He confronts the man and accidentally kills him. At the same time, another mysterious stalker with a weird mask appears and takes pictures of the accidental murder. For Roberto and his girlfriend Mina (Mimsy Farmer) it's the beginning of a nightmare, and more murders will ensue soon. Dario Argento directs.